a) Field of the Invention
The present invention relates to a building roof structure, and more particularly to an air permeation roof that utilizes an effect of natural air circulation to save energy and reduce temperature inside the building and of the roof.
b) Description of the Prior Art
An ordinary tin house can be built up quickly and therefore is applied to a gathering place, a resident house, a factory, a warehouse or a market that is built temporally. However, under direct exposure to sun, temperature inside the tin house can increase quickly. Therefore, a ceiling fan will be added under the roof of the tin house to reduce primarily the temperature inside the tin house.
Nevertheless, adding the ceiling fan under the roof of the tin house is very dangerous, not implemented easily and not pretty. Furthermore, as the ceiling fan is suspended high, objects or persons underneath the ceiling fan can be injured easily if the ceiling fan drops accidentally. In addition, according to the physical phenomenon that hot air rises up and cold air descends, hot air will be concentrated at a top inside the tin house. As the ceiling fan is installed in proximity to the top inside the tin house, when the ceiling fan is turned on, hot air at the top of the tin house will be blown downward, which only results in convection of the hot air inside the tin house and allows the people inside the tin house to feel like staying in an oven, without actually expelling out the hot air.
Accordingly, there are vendors who have designed a way of adding plural rooftop ventilation fans outside the tin house to achieve the air circulation effect by connecting indoor air with outdoor air. This method utilizes primarily natural wind to drive the ventilation fans, such that an air drafting effect can be formed by the ventilation fans and hot air inside the tin house can be expelled out. Besides that, air convection can be formed inside and outside the tin house.
However, this method can only activate the ventilation fans to rotate if there is natural wind. On the contrary, if there is no natural wind, then the hot air in the tin house is still not able to be expelled out effectively and quickly. In addition, as fan blades of the ventilation fans are not the air drafting blades, the air drafting efficiency is not high.